Over the years, many researchers have investigated the mechanism of the optical effects of incident light reflected from butterfly insect wings. However, only in recent years have significant advances been made to understand the mechanism behind this effect. The mechanism for creating the bright iridescence in butterfly wings has now been found to be the combined effects of diffraction and interference of light from elaborate arrays of multilayered sub-micrometer structures. These multilayered structures are present in an overlapping pattern, and form a domino-like photonic nanostructure.
As the development of a new type of photonic element by mimicking the butterfly's wings is very alluring, there have been attempts to imitate and reproduce the multilayered structures. One technique that has been utilised in an attempt to create a structure that mimics the optical effects of butterfly insect wings is the use of focused ion beam induced chemical vapour deposition (FIB-CVD) to manufacture such micro-structures. However, FIB-CVD has a number of disadvantages. One disadvantage is that the use of FIB-CVD lacks potential scalability and cost effectiveness. As such, commercial-scale manufacture using FIB-CVD is not economically viable.
Another method is the generation of nanometer-scale stepped patterns consisting of alternately TiO2 and SiO2 thin films, by the combination of lithography and electron beam deposition. However, the disadvantage of this method is that it requires multiple deposition steps of materials with different refractive indexes to obtain a multi-layered stacked structure. As such, the method is both complicated and time-consuming.
Despite the methods described above to emulate and replicate the multilayered structures on the butterfly wings, the development of cost-effect methods that can closely imitate the structural complexity of the butterfly wings still represents one of the technical challenges facing fabrication of such structures.
There is a need to provide a method of making a substrate having multi-layered structures that overcomes or at least ameliorates one or more of the disadvantages described above.